<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    var xhr = new XMLHttpRequest();
    xhr.onreadystatechange = function (){
        if (xhr.readyState == 4){
            if (xhr.status == 200){
                alert(xhr.responseText)
            }
        }

    };
    xhr.open('GET','')
    xhr.send(null)


    new Promise((resolve, reject  ) =>{
        setTimeout(() =>{
            resolve(1)
        })
    }).then(value => {
        console.log('value',value)
    }),reason =>{
        console.log('reason',reason

        )
    }
</script>
</body>
</html>